The present invention relates to a multi-layer resist which can be used in micro processing, and more particularly to a multi-layer resist wherein one or more thin films are placed between a Langmuir-Blodgett film (hereinafter referred to as "LB film") and a substrate.
The integration of semiconductor has been progressing, so a four megabit chip (4M-chip) goes into quantity production and a 16M-chip or 64M-chip begins to be made on an experimental basis. In order to realize such an integration, it is necessary to form a line of 0.7 .mu.m, 0.5 .mu.m, or 0.3 .mu.m in minimum width.
In view of the above-mentioned problem, EP-A-0308948 or Japanese Unexamined Patent Publication No. 63-191831 (Tokkyo Kokai No. 63-191831) proposes an LB film suitable for use of a single layer resist which is high in resolution and excellent in dry etching resistance.
However, there is a problem that when forming a very thin LB film on an uneven surface of a substrate, great unevennesses is formed in the LB film. As the steps of semiconductor processing proceed, the number of defects are increased.
Also, there is a problem that it is difficult to obtain a pattern with excellent resolution due to reflected light or scattered light from a substrate surface.
A conventional three-layer resist comprising a layer of a resist for forming an image, a silicon dioxide layer and a layer of an organic material having a dry etching property was already proposed. In order to obtain resolution of about 0.3 .mu.m, when using such a three-layer resist, it is important to shorten the wavelength of a light source used and to make the thickness of the image-forming resist film thin.
However, in the case of phenol-novolak positive resists which are generally used, it is difficult to obtain excellent patterns because of its strong absorption in the deep ultraviolet region. Also, according to spin coating method, it is difficult to coat thinly and uniformly without defects.
An object of the present invention is to provide a multi-layer resist with substantially no defects.
A further object of the present invention is to provide a micro processing process using such a multilayer resist.
These and other objects of the present invention will become apparent from the description hereinafter.